[exim] Filter Problem

    I newly installed lest version and  I create .forward file to under root
and exim users home directory , but My writen filters are not working ,
there is no error on log or anywhere but filters didn't work . Any knowledge
?  I want to discard some attachements , I know it possible with controlling
.exe,bat, bla bla but I want to filter x.bat attachemnt for example